I have a 15 amp battery charger with an ammeter on it, What does it mean when the meter goes to 10 amps then?

Question

down to zero amps, then back to 10 amps. It's doing this over and over. I am used to charging a battery and it will start out at about 15 amps then slowly go down to 2 or so amps and the green light will come on saying "fully charged".

Does the back and forth motion of the meter mean the battery is bad? It's a deep cycle battery.

Answer 1

That is wrong, wrong, wrong. It shouldn't go up to 10 amps unless the battery is fairly low, then it should gradually drop to trickle as the battery charges up. Try the charger on another battery, and if it does the same thing, it is faulty. If it doesn't do the same thing, then there is a problem with the first battery connections, or the battery itself.

Answer 2

The battery might have a thermistor in it that cuts the charging current when it gets too hot. When it cools down, it starts taking a charge again. The charger needs to be made for deep cycle batteries to work right.
A cracked battery post can cause that too. The crack heats up and you have a lousy connection until it cools down again.
The other thing would be a bad charger overheating. Try the charger on another battery, or try another charger on that battery to make sure.

Answer 3

The charger does that to keep from overheating the cells and warping them. They do this on maintenance free batteries now and it is normal. My charger does the same thing. There should be a switch on the charger that says normal. If you put it on that, then the amps won't drop off and it will charge faster..

Answer 4

Take the battery to an auto store and have it load tested. If it passes, your battery charger seems to have a problem. At least I've never seen one act that way in 40 years. If FordMan is correct, I'm ahead of the game when it happens to me.